The article doesn't mention Ultra Maritime's previous ownership situation, but the company's announcement of the deal from July does:

BOSTON, Massachusetts; LONDON, UK – Cobham Ultra, a portfolio company of Advent, a leading global private equity investor, today announced that it has agreed to sell Ultra Maritime, a worldwide leader in next-generation undersea warfare solutions, to Lockheed Martin, for USD $3.45 billion.

Since acquiring Ultra Maritime in 2022, Advent has partnered closely with the management team to transform the business into a unified, mission-focused enterprise dedicated to advancing undersea warfare solutions.

Ultra was already foreign owned.

This article shows how far back it goes:

The Woodside facility has been in business in the same location under various names since 1947 — most notably, Hermes Electronics Ltd. — and was purchased by U.K.-based Ultra Electronics in 1995 as the company’s first Canadian acquisition.

So for the last 25 years, the Dartmouth company has been part of Ultra Electronics, which also has a presence in the U.K., the U.S. and Australia.